Pyrolysis of automobile shredder residue in a laboratory scale screw type reactor

Abstract

Polymeric fraction of automobile shredder residue (ASR) was pyrolyzed in a laboratory scale screw type reactor under various conditions. All components of ASR and also a representative mixed sample of ASR were studied by thermogravimetric (TGA) analysis, differential scanning calorimetry (DSC), elemental analysis, bomb calorimetry and atomic emission spectrometry (AES). The ASR sample used in the laboratory pyrolysis apparatus contained mainly plastics, rubber, textiles, foam and other organics. The pyrolysis experiments were conducted at reactor temperatures ranging from 550 to 800°C, providing solid (30–34wt%), liquid (7–28wt%) and gas (42–65wt%) pyrolysis products. Composition of pyrolysis gases was measured online by a microchromatograph. By increasing the temperature, the content of hydrogen and CO in the gas fraction increased while that of light hydrocarbons decreased. The content of methane showed a maximum at 750°C. For pyrolysis char, its proximate and elemental composition, higher heating value and heavy metal content were determined. Char contained around 48wt% of fixed carbon; its sulfur content increased from 1.12wt% for char produced at 550°C to 2.31wt% for char produced at 800°C; its higher heating value varied between 14–19MJ/kg. Influence of the initial ASR composition was investigated as well. Increasing the content of rubber resulted in an increase of the char yield, while by increasing the plastic content, the gas yield increased. No significant effect of the ASR composition on the amount of liquid pyrolysis product was observed.